Patients with vestibular disorders commonly complain of vertigo, disequilibrium and oscillopsia. Results from studies on experimental animals is with unilateral and/or bilateral vestibular loss suggest that a proper program of exercises should enhance compensation. In human beings, however, only anecdotal evidence supports the use of exercises as treatment for vestibular disorders. This study will determine scientifically the effect of physical therapy on vestibular function. We will quantify the effects of exercises on the recovery of gaze stability and postural stability in two groups of patients: 1) those with unilateral vestibular loss due to surgical procedures (acoustic neuroma resection or vestibular nerve section) and 2) those with complete bilateral vestibular loss due to ototoxicity. Emphasis will be on the effect of early intervention on recovery. Patients will be studied before and after brief periods of exercises as well as over longer intervals. The results from the group will also be compared with a control group to determine the effectiveness of the treatment. We will develop a simple bedside test of VOR function using a visual acuity task during head rotation and will quantify VOR gain using the rotary chair test. In patients with complete vestibular loss, we will quantify the alternative oculomotor strategies used to stabilize gaze. We will also quantify postural stability using dynamic posturography as an indication of the patient's ability to use different sensory cues to maintain balance. The exercises used in this study will be based on our understanding of vestibular function and adaptation and on the strategies used by patients with bilateral vestibular loss to compensate for the lost vestibular function.